simplification of sums

*To*: mathgroup at yoda.physics.unc.edu (Mathematica mailing list)*Subject*: simplification of sums*From*: robert_nachbar at merck.com (Robert Nachbar)*Date*: Thu, 30 Jun 1994 08:53:24 -0500 (EDT)

hi, i'm using Mathematica and would like to manipulate various symbolic sums. in particular, given that Xbar=Sum[X[i],{i,n}]/n, i would like to be able to simplify Sum[(X[i]-Xbar)^2,{i,n}] to Sum[X[i]^2,{i,n}] - n Xbar^2 also, i would like to be able to distribute summation in general: Sum[a + b - c,{i,n}] -> Sum[a,{i,n}] + Sum[b,{i,n}] - Sum[c,{i,n}] and pull constant factors out of the sum Sum[2 a X[i],{i,n}] -> 2 a Sum[X[i],{i,n}] i've tried to write my own Rules for ReplaceAll, but without success. the package Algebra`SymbolicSum` does not seem to help. any suggestions out there? bob -- Dr. Robert B. Nachbar | Merck Research Laboratories | 908/594-7795 nachbar at merck.com | RY50S-100 | 908/594-4224 FAX | PO Box 2000 | | Rahway, NJ 07065 |